// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_IO_H
#define EIGEN_CXX11_TENSOR_TENSOR_IO_H

namespace Eigen {

namespace internal {

    // Print the tensor as a 2d matrix
    template <typename Tensor, int Rank> struct TensorPrinter
    {
        static void run(std::ostream& os, const Tensor& tensor)
        {
            typedef typename internal::remove_const<typename Tensor::Scalar>::type Scalar;
            typedef typename Tensor::Index Index;
            const Index total_size = internal::array_prod(tensor.dimensions());
            if (total_size > 0)
            {
                const Index first_dim = Eigen::internal::array_get<0>(tensor.dimensions());
                static const int layout = Tensor::Layout;
                Map<const Array<Scalar, Dynamic, Dynamic, layout>> matrix(const_cast<Scalar*>(tensor.data()), first_dim, total_size / first_dim);
                os << matrix;
            }
        }
    };

    // Print the tensor as a vector
    template <typename Tensor> struct TensorPrinter<Tensor, 1>
    {
        static void run(std::ostream& os, const Tensor& tensor)
        {
            typedef typename internal::remove_const<typename Tensor::Scalar>::type Scalar;
            typedef typename Tensor::Index Index;
            const Index total_size = internal::array_prod(tensor.dimensions());
            if (total_size > 0)
            {
                Map<const Array<Scalar, Dynamic, 1>> array(const_cast<Scalar*>(tensor.data()), total_size);
                os << array;
            }
        }
    };

    // Print the tensor as a scalar
    template <typename Tensor> struct TensorPrinter<Tensor, 0>
    {
        static void run(std::ostream& os, const Tensor& tensor) { os << tensor.coeff(0); }
    };
}  // namespace internal

template <typename T> std::ostream& operator<<(std::ostream& os, const TensorBase<T, ReadOnlyAccessors>& expr)
{
    typedef TensorEvaluator<const TensorForcedEvalOp<const T>, DefaultDevice> Evaluator;
    typedef typename Evaluator::Dimensions Dimensions;

    // Evaluate the expression if needed
    TensorForcedEvalOp<const T> eval = expr.eval();
    Evaluator tensor(eval, DefaultDevice());
    tensor.evalSubExprsIfNeeded(NULL);

    // Print the result
    static const int rank = internal::array_size<Dimensions>::value;
    internal::TensorPrinter<Evaluator, rank>::run(os, tensor);

    // Cleanup.
    tensor.cleanup();
    return os;
}

}  // end namespace Eigen

#endif  // EIGEN_CXX11_TENSOR_TENSOR_IO_H
